The present invention relates generally to a well clean out tool. More particularly, the present invention relates to a tool for removing sand and other debris from a column of water within a borehole of a well.
During well drilling, service and workover operations, quantities of sand and other solid materials along with large quantities of water tend to collect during certain procedures in the bottom of a borehole or on top of various tools in the borehole. In order to continue the desired operations, it is necessary to remove the sand and other solid material from the water within the borehole. Accordingly, it is desirable to provide a relatively simple tool for effectively removing such debris from the well.
Various well clean out tools or sand pumps have been proposed. However, some of the prior art pumps have been either complex or prone to breakage. Further, some of the prior art arrangements have required a large hydrostatic head in order to operate properly.
One prior art tool is disclosed in U.S. Pat. No. 4,190,113 issued Feb. 26, 1980 to Harrison. The well clean out tool in the Harrison patent comprises an elongated main body having a lower inlet end and an upper outlet end. A pump is provided at an upper end of the body for pumping fluid from the inlet through a chamber for retaining debris and out through the outlet. The pump includes a piston which reciprocates in a cylinder. The piston has a one-way valve therein which admits flow upwardly through the piston into the cylinder space above the piston, but prevents flow downwardly through the tool, Openings are provided in the cylinder walls and form the outlet of the tool. A piston rod attached to the piston is reciprocated to pull fluid up through the tool to be forced outwardly through the outlet openings upon an upstroke of the piston. The Harrison patent is limited to a well clean out tool including a stop arranged on the piston rod for jarringly engaging an upper closure member to provide a jarring action.
Another known sand pump, similar to that disclosed in the Harrison patent, is disclosed in U.S. Pat. No. 3,138,215 issued to June 23, 1964 to Cook. The Cook patent discloses a sand pump including a plurality of pistons slidably arranged upon a plunger shaft. A plurality of valves adapted to cooperate with the movable pistons are secured to the plunger shaft. The uppermost valve acts as a stop and is securely arranged upon the plunger.
Still a further sand pump or bailer similar to the Harrison patent is disclosed in U.S. Pat. No. 2,237,686 issued April 8, 1941 to Parr. The bailer in the Parr patent includes a barrel within which a reciprocable plunger is arranged. The plunger is operated by a cable extending to the surface and secured to one end of a stem having its other end secured to the plunger. Another sand pump is disclosed in U.S. Pat. No. 2,171,539 issued Sept. 5, 1939 to Burns. The Burns patent discloses two telescopic sections which define a pump. The pump also includes a pair of arms which are adapted to be swung upwardly during pumping action of the device to hold one of the telescopic sections within the well during the pumping stroke.
Other patents related in general to sand pumps and the like are disclosed in U.S. Pat. Nos. 563,055 issued June 30, 1896 to Palm; 1,537,201 issued May 12, 1925 to Swan; 2,000,750 issued May 7, 1935 to Gates; 2,180,935 issued Nov. 21, 1939 to Dumble; and 2,182,374 issued Dec. 5, 1939 to Dumble.
Accordingly, it is an object of the present invention to provide an improved clean out tool for wells.
A further object of the present invention is to provide a well clean out tool that is relatively simple in construction yet is strong and reliable in operation.
Still a further object of the present invention is to provide a well clean out tool which is efficient in operation and does not require a large hydrostatic head or large amounts of power to operate.
These objects and others are accomplished by a well clean out tool according to the present invention. The tool includes an elongated body having first and second ends adapted to be received within a well borehole. The elongated body is comprised of a plurality of subs secured together. A first sub at a lower portion of the body near the first end includes an inlet for fluid and debris from the well borehole. The first sub also includes a first valve for permitting flow toward the second end and for preventing fluid flow toward the first end. A second sub arranged above the first sub receives and retains fluid and debris passing through the first sub. A third sub arranged above the second sub includes a second valve for permitting flow toward the second end and for preventing flow toward the first end of the elongated body. A fourth sub is arranged above the third sub with the fourth sub including an outlet for returning fluid to the well bore.
The fourth sub further includes a pump for drawing fluid into the inlet and through the first, second and third subs out through the outlet. The pump comprises an elongated hollow piston which is reciprocatingly driven in relation to a casing of the fourth sub. A third valve at an end of the piston remote from the second end of the elongated body is provided for permitting flow into the interior of the piston and for preventing flow out through the end of the piston. The outlet comprises a plurality of openings in a longitudinal piston wall above the lower end of the piston and passages through the casing of the fourth sub near an upper end of the fourth sub.
In a preferred embodiment, the first and second valves each comprise a spring-biased flap valve. Such a flap valve permits substantially free passage of water and debris through the valve toward the second end of the elongated body while effectively preventing flow of fluid toward the first end. Still further, the third valve preferably comprises a ball and seat arrangement within the end of the piston.
Further in the preferred embodiment, an additional sub is arranged below the first sub that is adapted to engage solid material at the bottom of the borehole or an upper end of tools in the borehole. The additional sub may be a rock bit, fishing tool or another similar device.
In addition, an arrangement for guiding the piston during reciprocation is preferably provided along with an arrangement for closing an upper end of the hollow piston. The arrangement for guiding the piston also permits rotation of the entire tool when desired by rotation of the piston.